Method of cold-flanging straight-edged sheet metal



H. McCABE.

METHODOF COLD FLANGING STRAIGHT EDGED SHEET METAL.

APPLICATION FIL'ED APR. ll, I9l9. 1,368,342, Patented Feb. 15, 1921.

am no stares HUGH MCCABE, OF LAWRENCE, MASSACHUSETTS.

'METHOD OF COLD FLANGING STRAIGHT-EDGED SHEET METAL.

Specification of Letters Patent.

" Patented Feb. 15, 1921.

Application filed April 11, 1919. Serial No. 289,432.

To all whom it may concern:

Be it known that I, Home MGCABE, a citizen of the United States, residing at Lawrence, in the county of Essex and State of Massachusetts, have invented certain new and useful Improvements in Methods of Cold-Flanging hltraight-Edged Sheet Metal; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to a method of cold flanging straight edged sheet metal. The object of the invention is to provide a method of cold flanging straight edged sheet metal in which successive portions are bent downward to form a flange, involving the successive stretching of portions of the flange and the subsequent compression thereof, so as to avoid buckling the plate. To accomplish this object the invention consists in the method hereinafter described and particularly defined in the claims.

In my Patent No. 1,065,824, dated June 24, 1913, a method of flanging curved plates is disclosed. In the specification of this patent it is stated that the machine of the type disclosed in two earlier patents (Nos. 1,006,861 and 1,030,416) operates satisfactorily to bend a flange on the straight edge of a cold plate and while this is apparently correct it does not so operate on a curved edged plate. I have discovered where the plate is short and the flange is narrow the above is true'(or apparently true) but when the flange is wide and long there is an elongation of the lower or extreme edge of the flange which causes a strain of the plate, for example, I have found that when a 4 inch flange is formed in this manner upon a 6 foot plate, the resulting concavity of the upper edge amounts to about 1 inch. It is apparent that with much longer sheets and greater widths of flange that the resulting concavity would be materially greater.

I have discovered that the objectionable elongation which occurs in the fibers of the flange during the flanging operation may be successfully counteracted by compressing the flange longitudinally. The present in vention contemplates the formation of a flange along the straight edge of a metal sheet by turning down successive increments thereof, so that the fibers of the flange are longitudinally stretched a certain amount and subsequently compressing the fibers of the flange.

In the accompanying drawing Figures 1 and 2 illustrate diagrannnatically a portion of a plate showing one increment of the flange in a partially bent down position in side and front elevation respectively and Figs. 3 and 4 are similar views showing the plate after a second'increment of the flange has been turned down.

According to my invention the bent down portion in being turned from the plane of the sheet to an angle thereto stretches the portion A connecting the bent down portion 1 with the unbent portion of the plate, and the flange on the plate is formed by successively bending down portions of the edge with the result that there are a number of stretched portions in each flange so bent. These stretched portions would cause the strain of the plate, but in order to prevent such strain according to the present invention, the fibers of the edge of the plate are compressed ,after the flange is formed.

The longitudinal compression of the elongated or stretched portions of the flange may be accomplished in any convenient and desired manner. I have found that a flanging machine of the McCabe type, such as is illustrated in my Patent No. 1,164,732, may be used for accomplishing the longitudinal compression. When such a machine is used the body portion of the sheet is subjected to arching or strain so that the bending operation is utilized to elfect the longitudinal compression of the stretched or elongated portions of the flange.

It is within the purview of the invention that the compression of the fibers of the flange should follow each successive bending down oi a portion thereof, so that as the flange is formed first a portion 1 is bent down, an adjacent portion A is stretched, then another portion 2 is bent down and the first stretched portion A is compressed while another portion B beyond the second portion 2 being bent down is stretched so that as the forming of the flange progresses there are successivestretchings and compressings of portions of the edge of the plate being. formed into the flange. It is immaterial whether the compressings follow successively after the stretchings or whether at the completion of the formation of the flange the compressings are all accomplished. It will also be understood that the metal sheet may be of any shape as for in V stance a cylinder, so long as the edge to be flanged is straight.

Having thus described the invention What is claimed is: 1. The method of cold fianging straight edged sheet metal which consists in bending down successive portions of the straight edge of the sheet, such bending down being accompanied by a longitudinal stretching of the bent, down portion, and subjecting such stretched bent down portion to longi tudinal compression to shorten it longitudinally. I V "2. Thet'method of cold flanging straight edged sheet metal Which consists in bending down a portion of the edge of the sheet to 'form' an increment'of the flange, thereby stretching themetal between the end 01 the bent down portion and the portion of the sheet to be subsequently bent down, bending down a succeeding portion of the sheet to form another increment of the flange,

compressing the previously stretched por edged sheet metal which consists in bending down successive portions of the straight edge of the sheet, suchbending doWn being accompanled' by a longitudinal stretching of the bent down portion a certain amount,

and subjecting such stretched bent down portion to" longitudinal compression to shorten it the same amount longitudinally. HUGH MoCABE. 

